1. Field of the Invention
The present invention relates to laminated polymeric foam articles and a process for preparing the laminated polymeric foam article.
2. Description of Related Art
Polymeric foam articles have utility as thermally insulating materials. Polymeric foam articles serve as thermal insulation in building and construction applications, appliance applications and nearly any other application where thermal insulation is valuable. Increasing the thickness of polymeric foam articles tends to reduce the thermal conductivity (that is, increase thermal resistance) through the articles, all other properties being equal. However, increasing foam thickness is not necessarily easy, particularly for extruded polymeric foam articles.
Extrusion foam processes expel a foamable polymer composition through a foaming die that, to a large extent, controls the size and shape of resulting extruded polymeric foam. As the cross sectional area of the foaming die opening increases to enable manufacturing of larger cross section foam articles the extrusion process becomes more difficult to control. For example, foam surface skin begins to become irregular as pressures become harder to maintain constant. Hence, it becomes difficult to prepare quality extruded polymeric foam as the cross sectional dimensions (including thickness) of the polymeric foam increases.
One solution to preparing quality extruded polymeric foams of significant thickness is by laminating multiple thinner extruded polymeric foams together in a layered fashion. EP1734193A1, for example, describes a stacking and gluing multiple extruded polymeric foams together to form a thick thermoinsulating panel. U.S. patent application Ser. No. 61/100,830 ('830) also describes laminated polymer foams together to achieve a thick acoustically attenuating article. Foams in '830 are perforated all the way through prior to lamination in order to increase air flow through the foam using needles having a diameter of one millimeter or more. Unfortunately, merely laminating extruded polymeric foams together effectively and aesthetically can be challenging. Extruded polymeric foams typically have a polymer skin on their surfaces that are not perfectly planar. Therefore, it can be problematic to glue together extruded polymeric foam containing their skins since contact between foam surfaces may only be sporadic. Moreover, air gaps can exist between adjoining foam surfaces if the surfaces are not perfectly flat. Air gaps can draw and retain moisture, which is undesirable for thermal insulation.
EP1213118B1 discloses an advance in preparing laminated thermally insulating foam articles by first removing the skin surface from adjoining polymeric foams prior to adhering them together. By removing the skins the foam surfaces can be made planar and vapor can transfer with more freedom between the foams than if the skins remained. However, removing skin from foam surfaces requires a skiving step and produces a considerable amount of scrap polymer that must be either disposed of or recycled in some fashion.
It would be desirable to find a way to optimize adhesion between extruded polymeric foams without having to remove the skins of adjoining foam surfaces, particularly if tensile bond strengths at the interface exceed that of a unitary foam structure. Yet more desirable is if vapor could still transfer between foams across the adhesion interface.